“My father can do that too,” said Tinker proudly. “He’s a wizard at figures as well. He’s an inventor.”

“Ha! An inventor? And what does he invent?” asked Mr Wooh, eating his roll.

That was enough to set Tinker describing at once how wonderful his father was. “He can invent anything he’s asked for,” said the boy, proudly. “He invented a wonderful thing for keeping aeroplanes dead straight in the right direction — better than any idea before. He invented the sko-wheel, if you know what that is — and the electric trosymon, if you’ve ever heard of that. I don’t suppose you have, though. They’re too…”

“Wait, boy!” said Mr Wooh, sounding most interested. “These things I have heard of, yes. I do not know them, but I have certainly heard of them. Your father must be a very, very clever man, with a most unusual brain.”

Tinker swelled with pride. “Something got into the papers about his inventions a little while ago,” he said, “and reporters came down to see Dad, and his name was in the papers — but Dad was awfully cross about it. You see, he’s in the middle of the biggest idea he’s ever thought of and it messed up his work to have people coming to interview him — some of them even peered through the window, and went to see his wonderful tower, with its…”

“Tower? He has a tower?” said Mr Wooh, full of surprise. Before Tinker could answer, he received a hard poke from Julian’s finger. He turned crossly, to see Julian frowning fiercely at him. So was George. He went suddenly red in the face. Of course — he had been told never to talk about his father’s work. It was secret work, very secret.

He pretended to choke over a piece of meat, hoping that Julian would take the chance of changing the subject — and Julian did, of’ course!

“Mr Wooh, could you do a bit of magic reckoning with figures?” he asked. “I’ve heard that you can give the answers to any sum as quick as lightning.”

“That is true,” said Mr Wooh. “There is nothing that I cannot do with figures. Ask me anything you like, and I will give you the answer at once!”

“Well, Mr Wooh, answer this then,” cried Tinker. “Multiply sixty-three thousand, three hundred and forty-two by eighty thousand, nine hundred and fifty-three! Ha — you can’t do that in a hurry!”

“The answer is, in figures, 5127724926,” said Mr Wooh at once, with a slight bow. “That is an easy question, my boy.”

“Crumbs!” said Tinker, astounded. He turned to Julian. “Is that right, Ju?”

Julian worked out the sum on paper. “Yes. Absolutely correct. Whew!” he said. “You said that as quick as lightning!”

“Let me give him a sum to do!” cried George. ‘What

do you get if you multiply 602491 by 352, Mr Magician?’

“I get the figures 2-1-2-0-7-6-8-3-2,” said Mr Wooh, immediately. And once more Julian worked out the sum on paper. He raised his head and grinned. “Yes — correct. How do you do it so quickly?”